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Income Taxes - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended	12 Months Ended
	Mar. 30, 2020	Mar. 27, 2020	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Line Items]
Federal income tax rate				21.00%	21.00%	21.00%	35.00%
Increase (decrease) in net income due to exemption from complementary tax				$ 4.0	$ (54.0)
Increase (decrease) in diluted earnings per share due to exemption from complementary tax				$ 0.01	$ (0.10)
Possible decrease in unrecognized tax benefits within next 12 months				$ 30.0
Macau [Member] | MGM Grand Paradise SA [Member]
Income Tax Disclosure [Line Items]
Macau's complementary tax rate on distributions of gaming profits (as a percent)	12.00%			12.00%
Complementary tax				$ 1,500.0
Annual payments under the extended annual fee arrangement					$ 1.0	$ 1.0	$ 1.0
Payments under the extended annual fee arrangement			$ 0.3
Coronavirus Aid Relief And Economic Security Act
Income Tax Disclosure [Line Items]
Net operating losses carryback period		5 years
Income tax receivable		$ 206.0
Income tax benefit realized		$ 83.0

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